/*
   eXokernel Development Kit (XDK)

   Samsung Research America Copyright (C) 2013

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.
   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.

   As a special exception, if you link the code in this file with
   files compiled with a GNU compiler to produce an executable,
   that does not cause the resulting executable to be covered by
   the GNU Lesser General Public License.  This exception does not
   however invalidate any other reasons why the executable file
   might be covered by the GNU Lesser General Public License.
   This exception applies to code released by its copyright holders
   in files containing the exception.
*/


#include <common/rand.h>

/* The array for the state vector */
static unsigned long long mt[NN];
/* mti==NN+1 means mt[NN] is not initialized */
static int mti = NN + 1;

/* initializes mt[NN] with a seed */
void init_genrand64(unsigned long long seed) {
  mt[0] = seed;
  for (mti = 1; mti < NN; mti++)
    mt[mti] =
        (6364136223846793005ULL * (mt[mti - 1] ^ (mt[mti - 1] >> 62)) + mti);
}

/* initialize by an array with array-length */
/* init_key is the array for initializing keys */
/* key_length is its length */
void init_by_array64(unsigned long long init_key[],
                     unsigned long long key_length) {
  unsigned long long i, j, k;
  init_genrand64(19650218ULL);
  i = 1;
  j = 0;
  k = (NN > key_length ? NN : key_length);
  for (; k; k--) {
    mt[i] =
        (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 62)) * 3935559000370003845ULL)) +
        init_key[j] + j; /* non linear */
    i++;
    j++;
    if (i >= NN) {
      mt[0] = mt[NN - 1];
      i = 1;
    }
    if (j >= key_length) j = 0;
  }
  for (k = NN - 1; k; k--) {
    mt[i] =
        (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 62)) * 2862933555777941757ULL)) -
        i; /* non linear */
    i++;
    if (i >= NN) {
      mt[0] = mt[NN - 1];
      i = 1;
    }
  }

  mt[0] = 1ULL << 63; /* MSB is 1; assuring non-zero initial array */
}

/* generates a random number on [0, 2^64-1]-interval */
unsigned long long genrand64_int64() {
  int i;
  unsigned long long x;
  static unsigned long long mag01[2] = {0ULL, MATRIX_A};

  if (mti >= NN) { /* generate NN words at one time */

    /* if init_genrand64() has not been called, */
    /* a default initial seed is used     */
    if (mti == NN + 1) init_genrand64(5489ULL);

    for (i = 0; i < NN - MM; i++) {
      x = (mt[i] & UM) | (mt[i + 1] & LM);
      mt[i] = mt[i + MM] ^ (x >> 1) ^ mag01[(int)(x & 1ULL)];
    }
    for (; i < NN - 1; i++) {
      x = (mt[i] & UM) | (mt[i + 1] & LM);
      mt[i] = mt[i + (MM - NN)] ^ (x >> 1) ^ mag01[(int)(x & 1ULL)];
    }
    x = (mt[NN - 1] & UM) | (mt[0] & LM);
    mt[NN - 1] = mt[MM - 1] ^ (x >> 1) ^ mag01[(int)(x & 1ULL)];

    mti = 0;
  }

  x = mt[mti++];

  x ^= (x >> 29) & 0x5555555555555555ULL;
  x ^= (x << 17) & 0x71D67FFFEDA60000ULL;
  x ^= (x << 37) & 0xFFF7EEE000000000ULL;
  x ^= (x >> 43);

  return x;
}

/* generates a random number on [0, 2^63-1]-interval */
long long genrand64_int63(void) { return (long long)(genrand64_int64() >> 1); }

/* generates a random number on [0,1]-real-interval */
double genrand64_real1(void) {
  return (genrand64_int64() >> 11) * (1.0 / 9007199254740991.0);
}

/* generates a random number on [0,1)-real-interval */
double genrand64_real2(void) {
  return (genrand64_int64() >> 11) * (1.0 / 9007199254740992.0);
}

/* generates a random number on (0,1)-real-interval */
double genrand64_real3(void) {
  return ((genrand64_int64() >> 12) + 0.5) * (1.0 / 4503599627370496.0);
}
